It has been known in general that a silicone oil, etc., modifies a surface of an inorganic oxide fine powder. For example, in the “TECHNICAL BULLETIN Aerosil No.22” (published by Nippon AEROSIL Co.), which is published by the inventors, a silica powder dry-treated with polydimethylsiloxane, is shown, and an example was shown, in which said silica powder is used for an epoxy adhesives. Moreover, in U.S. Pat. Nos. 4,477,607, and 4,713,405, regarding the silica powder dry-treated with polydimethylsiloxane, the examples are shown, in which said silica powder is added to a cyanoacrylate adhesive as a viscosity increasing agent.
Such a surface modified inorganic oxide powder is used widely for the purpose of the viscosity increasing or an addition of thixotropy, as a filler of the polar resin, such as an epoxy resin, an urethane resin, and a polyester etc. In such application, viscosity increasing, thixotropy, and stability with the passage of time are important factors. In recently, the additional agent is required, which can give high viscosity and high thixotropy by less addition than before use, and also has the excellent stability with the passage of time.
Present inventors proposed previously the inorganic oxide powder, which is useful about improvement of fluidity, prevention of coagulation, and adjustment of electrostatic charge, etc., of the powder materials, with such viscosity increasing and filling for reinforcement (Japanese Patent Laid Open, Hei 09-59533). This powder is the surface modified inorganic oxide powder made by two stages process, wherein the inorganic oxide powder, such as silica, is treated with alkylsilane, and further with an organo-poly-siloxane having functional groups, such as a halogen group, a hydroxyl group, and an alkoxy group, at the both ends of main chain. Consequently, said oxide powder has the excellent stability with the passage of time and the surface treatment effectiveness.